As the proventriculus plays an important role in food digestion and there are differences in morphological and functional characteristics among different avian species, this study was carried out. A total of 54 female and males Ross broiler chicks at age 3, 7 days and then at weekly intervals until week 8 were used. The proventriculus were collected and fixed in 15% buffered formalin solution. Histologic sections of 5µm of thickness were obtained and they were stained routinely with hematoxylin-eosin and special stainings: Alcian blue, Orcein, Masson’s trichrome, PAS and Gomori’s method for reticular fibers. The results showed that by age increasing, the height of mucosal folds (particularly anastomoses), lymphatic aggregations, the number and frequency of superficial mucosal glands, the size and number of deep mucosal glands, thickness of muscularis mucosa, tunica muscularis (particularly inner circular) and serosa (particularly adipose tissue) were also increased. The shape of the deep glands was varied but polygonal, elliptical and triangular structures more prominent. The duct branching of these glands were increased with age. There was not a significant histological difference between male and female chickens. Our observations on the general histological structures of proventriculus were similar to native chickens stated in literature, but there were also some differences. The muscularis mucosa is thick and continuous. The deep glands are compound tubular and located in the lamina propria. Lymphatic aggregations are present within the connective tissue between the compound glands, and beneath their central unique ducts.